Embolic devices for occluding body lumens

ABSTRACT

An embolic device for placement in a body lumen, includes: an elongated member having a linear configuration when in room temperature, the elongated member being configured to form a first three-dimensional structure in response to body temperature; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment being located between the first segment and the third segment; wherein the first segment and the third segment are configured to change their respective shapes in response to the body temperature; and wherein the second segment that is located between the first segment and the third segment has a shape that is independent of the body temperature.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.16/679,646 filed on Nov. 11, 2019. The entire disclosure of the aboveapplication is expressly incorporated by reference herein.

FIELD

The field of the disclosure relates to medical devices and methods foroccluding body lumens, and more specifically, to medical devices andmethods for occluding aneurysms.

BACKGROUND

An aneurysm is a dilation of a blood vessel that poses a risk to healthfrom the potential for rupture, clotting, or dissecting. Rupture of ananeurysm in the brain causes stroke, and rupture of an aneurysm in theabdomen causes shock. Cerebral aneurysms are usually detected inpatients as the result of a seizure or hemorrhage and can result insignificant morbidity or mortality.

There are a variety of materials and devices which have been used fortreatment of aneurysms, including platinum and stainless steelmicrocoils, polyvinyl alcohol sponges (Ivalone), and other mechanicaldevices. For example, vaso-occlusion devices are surgical implements orimplants that are placed within the vasculature of the human body,typically via a catheter, either to block the flow of blood through avessel making up that portion of the vasculature through the formationof an embolus, or to form such an embolus within an aneurysm stemmingfrom the vessel.

Sometimes, when a vaso-occlusion device is being carried within thecatheter, the vaso-occlusion device is elastically bent to conform witha profile of the catheter. This elastic bending of the vaso-occlusiondevice creates various pressure points against the inner surface of thecatheter, which may be undesirable because it makes advancement of thevaso-occlusion device relative to the catheter harder. In some cases,increased axial force may need to be exerted in order to push thevaso-occlusion device distally. This increased axial force may sometimescause premature buckling of the vaso-occlusion device inside thecatheter.

Also, a vaso-occlusion device may assume a certain three-dimensionalshape after it is deployed outside the catheter. If the deployedvaso-occlusion device is too stiff, it may not conform with a shape ofthe body cavity intended to be occluded by the vaso-occlusion device. Onthe other hand, if the deployed vaso-occlusion device is too flexible,then the vaso-occlusion device may not retain its shape, and may beunintentionally bent into an undesirable shape, rendering it incapableof occluding the body cavity.

New embolic devices for occluding body lumens that address the aboveproblems would be desirable.

SUMMARY

An embolic device for placement in a body lumen, includes: an elongatedmember having a linear configuration when in room temperature, theelongated member being configured to form a first three-dimensionalstructure in response to body temperature; wherein the elongated membercomprises a first segment, a second segment, and a third segment, thesecond segment being located between the first segment and the thirdsegment; wherein the first segment and the third segment are configuredto change their respective shapes in response to the body temperature;and wherein the second segment that is located between the first segmentand the third segment has a shape that is independent of the bodytemperature.

Optionally, the first segment is configured to form a first part of aloop, and the third segment is configured to form a second part of theloop in response to the body temperature.

Optionally, the first segment is configured to form a first loop, andthe third segment is configured to form a second loop, in response tothe body temperature.

Optionally, the first segment has a first length, the second segment hasa second length, and the third segment has a third length; and whereinthe second length of the second segment is shorter than the first lengthof the first segment, and is also shorter than the third length of thethird segment.

Optionally, the second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Optionally, the elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when the fourth segment is in the roomtemperature, and is also martensitic when the fourth segment is in thebody temperature.

Optionally, the first segment is martensitic when the first segment isin the room temperature, and is austenitic when the first segment is inthe body temperature.

Optionally, the second segment is martensitic when the second segment isthe room temperature, and is martensitic when the second segment is inthe body temperature.

Optionally, the three-dimensional structure comprises a plurality ofloops, and wherein the first segment, the second segment, and the thirdsegment are parts of one of the loops.

Optionally, the elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment areconfigured to change their respective shapes in response to the bodytemperature; and wherein the fifth segment that is located between thefourth segment and the sixth segment has a shape that is independent ofthe body temperature.

An embolic device for placement in a body lumen, includes: an elongatedmember having a linear configuration when in room temperature, theelongated member being configured to form a first three-dimensionalstructure in response to body temperature; wherein the elongated membercomprises a first segment, a second segment, and a third segment, thesecond segment being located between the first segment and the thirdsegment; wherein the first segment is martensitic when the first segmentis in the room temperature, and is austenitic when the first segment isin the body temperature; and wherein the second segment is martensiticwhen the second segment is in the room temperature, and is alsomartensitic when the second segment is in the body temperature.

Optionally, the first segment is configured to form a first part of aloop, and the third segment is configured to form a second part of theloop, in response to the body temperature.

Optionally, the first segment is configured to form a first loop, andthe third segment is configured to form a second loop, in response tothe body temperature.

Optionally, the first segment has a first length, the second segment hasa second length, and the third segment has a third length; and whereinthe second length of the second segment is shorter than the first lengthof the first segment, and is also shorter than the third length of thethird segment.

Optionally, the second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Optionally, the elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when in the room temperature, and isalso martensitic when the fourth segment is the body temperature.

Optionally, the three-dimensional structure comprises a plurality ofloops, and wherein the first segment, the second segment, and the thirdsegment are parts of one of the loops.

Optionally, the elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment aremartensitic when the fourth segment and the sixth segment are in theroom temperature, and are austenitic when the fourth segment and thesixth segment are in the body temperature; and wherein the fifth segmentis martensitic when the fifth segment is in the room temperature, and isalso martensitic when the fifth segment is in the body temperature.

A method of occluding a body lumen performed by an embolic device havingan elongated member, the elongated member comprising a first segment, asecond segment, and a third segment, wherein the second segment isbetween the first segment and the third segment, includes: undergoing afirst shape change by the first segment of the elongated member inresponse to body temperature; undergoing a second shape change by thesecond segment of the elongated member in response to force; andundergoing a third shape change by the third segment of the elongatedmember in response to the body temperature.

Optionally, the first segment is martensitic when the first segment isin the room temperature, and is austenitic when the first segment is inthe body temperature; and wherein the second segment is martensitic whenthe second segment is in the room temperature, and is also martensiticwhen the second segment is in the body temperature.

Optionally, the first segment forms a first part of a loop, and thethird segment forms a second part of the loop, in response to the bodytemperature.

Optionally, the first segment forms a first loop, and the third segmentforms a second loop, in response to the body temperature.

Optionally, the first segment has a first length, the second segment hasa second length, and the third segment has a third length; and whereinthe second length of the second segment is shorter than the first lengthof the first segment, and is also shorter than the third length of thethird segment.

Optionally, the second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Optionally, the elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when in the room temperature, and isalso martensitic when the fourth segment is the body temperature.

Optionally, the three-dimensional structure comprises a plurality ofloops, and wherein the first segment, the second segment, and the thirdsegment are parts of one of the loops.

Optionally, the elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment aremartensitic when the fourth segment and the sixth segment are in theroom temperature, and are austenitic when the fourth segment and thesixth segment are in the body temperature; and wherein the fifth segmentis martensitic when the fifth segment is in the room temperature, and isalso martensitic when the fifth segment is in the body temperature.

Other and further aspects and features will be evident from reading thefollowing detailed description.

DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of embodiments, in whichsimilar elements are referred to by common reference numerals. Thesedrawings are not necessarily drawn to scale. In order to betterappreciate how the above-recited and other advantages and objects areobtained, a more particular description of the embodiments will berendered, which are illustrated in the accompanying drawings.

These drawings depict only exemplary embodiments and are not thereforeto be considered limiting in the scope of the claims.

FIG. 1 illustrates a medical device having a catheter for delivering anembolic device.

FIG. 2 illustrates the medical device of FIG. 1 , particularly showing adistal segment of the embolic device being delivered out of thecatheter.

FIG. 3 illustrates an example of the medical device of FIG. 1 ,particular showing the device's shape when in room temperature.

FIG. 4 illustrates the medical device of FIG. 3 , particular showing thedevice's shape when in body temperature.

FIG. 5 illustrates another example of the medical device of FIG. 1 ,particular showing the device's shape when in room temperature.

FIG. 6 illustrates the medical device of FIG. 5 , particular showing thedevice's shape when in body temperature.

FIG. 7 is a stress-strain graph, particularly showing an effect ofthermal cycling.

FIGS. 8A-8B illustrate a method of using the medical device of FIG. 1 .

FIG. 9 illustrates a method of delivering an embolic device into ananeurysm.

DETAILED DESCRIPTION

Various embodiments are described hereinafter with reference to thefigures. It should be noted that the figures are not drawn to scale andthat elements of similar structures or functions are represented by thesame reference numerals throughout the figures. It should also be notedthat the figures are only intended to facilitate the description of theembodiments. They are not intended as an exhaustive description of theinvention or as a limitation on the scope of the invention. In addition,an illustrated embodiment needs not have all the aspects or advantagesshown. An aspect or an advantage described in conjunction with aparticular embodiment is not necessarily limited to that embodiment andcan be practiced in any other embodiments even if not so illustrated, orif not so explicitly described.

FIG. 1 illustrates a medical device 10 having a catheter 20 fordelivering an embolic device 100 in a body lumen. The catheter 20 has adistal end 22, a proximal end 24, and a catheter body 26 extendingbetween the distal end 22 and the proximal end 24. The embolic device100 is contained within a lumen 28 of the catheter 20. The medicaldevice 10 further includes a shaft 30 located in the lumen 28 forpushing the embolic device 100 out of the lumen 28 of the catheter 20.

As shown in FIG. 1 , the embolic device 100 is made from an elongatedmember 102 having a distal end 104, a proximal end 106, and a body 108extending between the distal end 104 and the proximal end 106. Theelongated member 102 of the embolic device 100 has a linearconfiguration (e.g., a straight profile) when being in room temperatureinside the catheter 20. The elongated member 102 is configured to form athree-dimensional structure 112 in response to body temperature when theelongated member 102 is delivered outside the catheter 20 into apatient's body (FIG. 2 ).

FIG. 3 illustrates an example of the embolic device 100. As shown in thefigure, the elongated member 102 of the embolic device 100 has a linearconfiguration that is relatively straight when in room temperature. Theelongated member 102 is configured to form the three-dimensionalstructure in response to body temperature. The straight profile of theelongated member 102 in the catheter 20 is thus mainly due to theelongated member 102 being in room temperature, and it is not mainly dueto any mechanical straightening caused by the catheter 20. This featureis advantageous because it reduces friction between the elongated member102 and the inner wall of the catheter 20 so that the embolic device 100can be easier advanced distally. This feature also allows a longerembolic device 100 to be delivered if needed.

In the illustrated embodiments, the elongated member 102 has a firstsegment 300, a second segment 302, and a third segment 304. The secondsegment 302 is located between the first segment 300 and the thirdsegment 304. The first segment 300 and the third segment 304 areconfigured to change their respective shapes in response to the bodytemperature. The second segment 302 that is located between the firstsegment 300 and the third segment 304 has a shape that is independent ofthe body temperature.

It should be noted that the term “body temperature”, as used in thisspecification, may refer to a range of temperature, such as atemperature range of 95 F to 107 F, or more preferably a temperaturerange of 96 F to 100 F, or more preferably a temperature range of 97 Fto 99 F. Also, as used in this specification, the term “roomtemperature” may refer to any temperature that is different from thebody temperature. For example, room temperature may be any temperaturethat is lower than body temperature. In some embodiments, the roomtemperature may be any temperature that is at least 10 F below the bodytemperature, or that is at least 20 F below the body temperature.

In the illustrated embodiments, the first segment 300 is martensiticwhen the first segment 300 is in the room temperature, and is austeniticwhen the first segment 300 is in the body temperature. The secondsegment 302 is martensitic when the second segment 302 is the roomtemperature, and is martensitic when the second segment 302 is in thebody temperature. The third segment 304 is martensitic when the thirdsegment 304 is in the room temperature, and is austenitic when the thirdsegment 304 is in the body temperature. Accordingly, the first and thirdsegments 300, 304 are reversible Martensite segments that allow thefirst and third segments 300, 304 to have a relatively straight profilewhen in room temperature, and that allow the first and third segments300, 304 to change to Austenite segments in response to bodytemperature. On the other hand, the second segment 302 is anirreversible Martensite segment that allows the second segment 302 tohave a relatively straight profile when in both room temperature andbody temperature.

In the illustrated embodiments, the second segment 302 is softer thanthe first segment 300 and the third segment 304. This allows the secondsegment 302 to more easily bend in response to force compared to thefirst and third segments 300, 304.

It should be noted that as used in this specification, the term“straight” may be used to describe a delivery shape of the embolicdevice 100 that is rectilinear or curvilinear, as long as the deliveryshape has a curvature that is smaller than a curvature of the embolicdevice 100 in its deployed shape.

As shown in FIG. 4 , the elongated member 102 is configured to form thethree-dimensional structure 112 that comprises a plurality of loops 400in response to body temperature after the elongated member 102 isdeployed. As shown in the figure, the first segment 300, the secondsegment 302, and the third segment 304 are parts of one of the loops400. Thus, the first segment 300 is configured to form a first part of aloop 400, and the third segment 304 is configured to form a second partof the same loop 400 in response to the body temperature.

As shown in the figure, the elongated member 102 further comprises afourth segment 410, a fifth segment 412, and a sixth segment 414 thatare parts of another one of the loops 400. The fifth segment 412 isbetween the fourth segment 410 and the sixth segment 414. The fourthsegment 410 and the sixth segment 414 are configured to change theirrespective shapes in response to the body temperature. The fifth segment412 that is located between the fourth segment 410 and the sixth segment414 has a shape that is independent of the body temperature. In someembodiments, the fourth segment 410 and the sixth segment 414 aremartensitic when the fourth segment 410 and the sixth segment 414 are inthe room temperature, and are austenitic when the fourth segment 410 andthe sixth segment 414 are in the body temperature; and wherein the fifthsegment 412 is martensitic when the fifth segment 412 is in the roomtemperature, and is also martensitic when the fifth segment 412 is inthe body temperature.

In some embodiments, the elongated member 102 may include multiple setsof three segments, with each set of the three segments being configuredto form a loop (or other desired curvilinear shape) for thethree-dimensional structure 112. In each set of the three segments, thefirst and the last segments are configured to change shape in responseto body temperature, and the second segment that is between the firstand the third segments has a shape that is independent of the bodytemperature. Thus, when the elongated member 102 is delivered fromoutside the patient to inside the patient, the elongated member 102 issubjected to a change in temperature from room temperature to bodytemperature. As a result, the first and third segments in each of thesets of the elongated member 102 will change their shapes in response tothe body temperature, and the second segments in the sets of theelongated member 102 will not respond to the body temperature and willnot changing their shapes due to the body temperature.

In some embodiments, the first segment 300 has a first length, thesecond segment 302 has a second length, and the third segment 304 has athird length. The second length of the second segment 302 is shorterthan the first length of the first segment 300, and is also shorter thanthe third length of the third segment 304. For example, the secondlength of the second segment 203 that is between the first segment 300and the third segment 304 may be less than 50% of the first length ofthe first segment, and is also less than 50% of the third length of thethird segment.

In the above embodiments, the second segment 302 is described as beingbetween the first segment 300 and the third segment 304, wherein allthree segments 300, 302, 304 are parts of a loop. In other embodiments,the second segment 302 may be located at other positions. For example,in other embodiments, the second segment 302 may be located closer toone end of a loop. In such cases, the respective lengths of the firstand third segments 300, 304 may be different from each other. As anotherexample, in other embodiments, the second segment 302 may be locatedbetween two loops. In such cases, the first segment 300 is configured toform a first loop, and the third segment 304 is configured to form asecond loop, in response to the body temperature. The second segment 302located between the two loops (formed by the first and third segments300, 304) does not change shape in response to the body temperature.Instead, the second segment 302 may be configured to change shape inresponse to force. In some cases, the second segment 302 may be locatedat an inflection point between two loops.

Also, in other embodiments, instead of having only one irreversibleMartensite segment (e.g., segment 302) for each loop 400, the embolicdevice 100 may have multiple irreversible Martensite segments for eachloop 400.

In one or more embodiments described herein, the embolic device 100 mayoptionally further include a segment at its proximal end. FIG. 5illustrates another example of the embolic device 100. The embolicdevice 100 is similar to the embolic device 100 described with referenceto FIGS. 3-4 , except that the embolic device 100 further includes asegment 500 at its proximal end. As shown in FIG. 5 , the embolic device100 includes the first, second, and third segments 300, 302, 304 assimilarly described. However, the embolic device 100 further includes afourth segment 500 at the proximal end of the elongated member 102. Thefourth segment 500 does not change shape in response to bodytemperature. As shown in FIG. 6 , after the embolic device 100 issubjected to body temperature, a majority of the length of the elongatedmember 102 changes shape to form the three-dimensional structure 112.However, the fourth segment 500 remains straight and does not change itsshape. Instead, the fourth segment 500 is configured to change shape inresponse to force. For example, when the embolic device 100 with thefourth segment 500 is delivered into an aneurysm, the interior wall ofthe aneurysm, or other parts of the embolic device 100 that have alreadybeen delivered inside the aneurysm, may exert a force on the fourthsegment 500 when the fourth segment 500 is pushed out of the catheter20. This will cause the fourth segment 500 to bend. In some embodiments,the fourth segment 500 is martensitic when the fourth segment is in theroom temperature, and is also martensitic when the fourth segment 500 isin the body temperature. Also, in some embodiments, the fourth segment500 is softer than a segment with shape-memory characteristic (e.g.,first segment 300, third segment 302, etc.). Accordingly, the fourthsegment 500 can bend easier when an external force is applied. Thisallows the fourth segment 500 to be formed into any shape, depending ona direction and magnitude of the external force. In some cases, thefourth segment 500 may be configured for filling purpose to fill a spaceinside a body cavity, such as an aneurysm. In some embodiments, thefourth segment 500 may have a length that is greater than a length of apreceding loop 400. For example, the fourth segment 500 may have alength that is equal to 1×, 2×, 3× or 4× the length of the segmentforming a preceding loop 400.

In some embodiments, the fourth segment 500 may be made from the samematerial as that for segment 302, and may have the same mechanicalproperty as that of segment 302. In other embodiments, the fourthsegment 500 may be softer than the segment 302.

In the illustrated embodiments, the loops 400 of the three-dimensionalstructure 112 are connected by respective inflection points, which allowadjacent loops 400 to form reverse curvatures. In other embodiments,adjacent loops 400 of the three-dimensional structure 112 may not formreverse curvatures. Furthermore, in other embodiments, instead of loops,the first three-dimensional structure 112 may have other structuralelements with shapes that are not loops.

In some embodiments, the curvatures of the loops 400 of thethree-dimensional structure 112 may be the same. In other embodiments,one or more of the loops 400 may be different from another one of theloops 400 in the three-dimensional structure 112. For example, in someembodiments, the three-dimensional structure 112 may have a first loop400 with a first curvature, and a second loop 400 proximal to the firstloop 400, wherein the second loop 400 may have a second curvature thatis higher than the first curvature of the first loop 400. In otherembodiments, the three-dimensional structure 112 may have a first loop400 with a first curvature, and a second loop 400 proximal to the firstloop 400, wherein the second loop 400 may have a second curvature thatis lower than the first curvature of the first loop 400. As used in thisspecification, “curvature” may be defined as 1/R, where R may be thesmallest radius of curvature associated with the curve.

In some embodiments, the three-dimensional structure 112 has at leasttwo loops 400 (e.g., at least two adjacent loops 400) with respectiveloop dimensions that do not vary by more than 10%, and preferably thatdo not vary by more than 5%. For example, in one implementation, thethree-dimensional structure 112 may have loops 400 with the same loopdimension (e.g., loop width or diameter). In other embodiments, thethree-dimensional structure 112 may have loops 400 with respective loopdimensions that vary by more than 10%.

In addition, in some embodiments, the loops 400 in the three-dimensionalstructure 112 have respective loop dimensions that reduce along thelength of the elongated member 102 from the distal-to-proximaldirection. This feature is advantageous because it assists the elongatedmember 102 in forming different filling structures that are smaller thanthe previous ones, thereby allowing the subsequent filling structures tofit within the previous ones.

In some embodiments, a first portion of the embolic device 100 may havea first width, and a second portion of the embolic device 100 that isproximal to the first portion may have a second width that is less thanthe first width. Alternatively or additionally, the first portion of theembolic device 100 may have a first thickness, and the second portion ofthe embolic device 100 may have a second thickness that is less than thefirst thickness. In one implementation, the elongated member 102 may bea braided structure, and the narrower width and/or thickness of thesecond portion of the embolic device 100 may be accomplished by usingfewer strands of fiber to form the braid for the second portion comparedto the number of strands of fiber used to form the braid for the firstportion. Alternatively, the narrower width (or thickness) of the secondportion of the embolic device 100 may be accomplished by cutting orgrinding away (e.g., using laser cutter, grinder, etc.) some of themember that is used to form the second portion. As another alternative,the first and second portions of the embolic device 100 may be formedfrom separate members with different respective cross-sectionaldimensions. In such cases, the members may be secured to each other,e.g., using adhesive, weld, fusion, mechanical coupler, etc. It shouldbe noted that the terms “width” and “thickness” may refer to the longerand shorter dimensions of a cross section in some cases, such as crosssection having a rectangular shape or an elliptical shape. However, useof either of these terms should not imply that the cross section has anelongated shape. For example, width or thickness of a cross section mayrefer to a cross sectional dimension of a circular cross section, asquare cross section, a hexagon cross section, a pentagon cross section,etc.

Also, in some embodiments, the angles (between adjacent loops 400) ofthe three-dimensional structure 112 may progressively reduce in thedistal-to-proximal direction along the length of the elongated member102. This feature is advantageous because it may allow a distal portionof the elongated member 102 to form a first part of a three-dimensionalstructure 112 that is along a perimeter of a body cavity, and also mayallow a proximal portion of the elongated member 102 to form a secondpart of the three-dimensional structure 112 that can fit within thefirst part of the three-dimensional structure 112. In oneimplementation, a first portion of the elongated member 102 may beconfigured to form a first plurality of loops 400 with a first pluralityof angles between adjacent ones of the first plurality of loops 400, anda second portion of the elongated member 102 may be configured to form asecond plurality of loops 400 with a second plurality of angles betweenadjacent ones of the second plurality of loops 400. The first pluralityof angles may be the same as each other, and the second plurality ofangles may be the same as each other. However, the first plurality ofangles may be larger than the second plurality of angles.

As discussed, in some embodiments, the elongated member 102 may haveprogressively reducing angles between adjacent loops from distal end toproximal end of the elongated member 102. This allows the elongatedmember 102 to fill a body cavity from “outside-towards-inside” so thatan outer space within the body cavity is filled first before the innerspace in the aneurysm. In other embodiments, the elongated member 102may have progressively increasing angles between adjacent loops fromdistal end to proximal end of the elongated member 102. This allows theelongated member 102 to fill the body cavity from“inside-towards-outside” so that an inner space within the body cavityis filled first before the outer space in the body cavity.

In some embodiments, the elongated member 102 of the embolic device 100may be a braided structure. In one implementation, the elongated member102 may be formed by twenty-four strands of fibers that are braided.Alternatively, other numbers of strands of fibers may be used to formthe elongated member. Also, in some embodiments, a proximal portion ofthe elongated member 102 may be formed using more strands compared to adistal portion of the elongated member 102. In other embodiments, thedistal portion of the elongated member 102 may be formed using morestrands compared to the proximal portion of the elongated member 102,thereby making the distal portion stiffer compared to the proximalportion.

In other embodiments, the elongated member 102 of the embolic device 100may be a coil. In such cases, the elongated member 102 has a primaryshape that is a coil, and the coil may then be bent to form a desiredsecondary shape (deployed shape).

In further embodiments, the elongated member 102 of the embolic device100 may be a solid continuous member. In such cases, the solidcontinuous member has a primary shape that is straight, and the solidcontinuous member may then be bent to form a desired secondary shape(deployed shape).

In one or more embodiments described herein, the length of the elongatedmember 102 of the embolic device 100 may be anywhere from 15 cm to 50cm, or from 25 cm to 45 cm, or from 30 to 40 cm. In other embodiments,the length of the elongated member 102 of the embolic device 100 may beless than 15 cm or more than 40 cm.

Also, in one or more embodiments described herein, the elongated member102 of the embolic device 100 may be made from any suitable materials.By means of non-limiting examples, the elongated member 102 of theembolic device 100 may be made from Nitinol®, AuPt, stainless steel,platinum, other metals, other alloys, or any combination of theforegoing.

In some embodiments, each previous portion of the elongated member 102forms a filling structure that allows accommodation of later portion(s)of the elongated member 102. This allows different layers of structuresto be progressively delivered into the aneurysm in a nestingconfiguration to fill the aneurysm from the periphery towards the centerof the aneurysm. In some embodiments, a first portion of the elongatedmember 102 may have a first set of loops, a second portion of theelongated member 102 proximal to the first portion may have a second setof loops, a third portion of the elongated member 102 proximal to thesecond portion may have a third set of loops, etc. The first set ofloops may have loop widths that are the same in size, or that decreasein size in the distal-to-proximal direction. Similarly, the second setof loops may have loop widths that are the same in size, or thatdecrease in size in the distal-to-proximal direction. Also, the thirdset of loops may have loop widths that are the same in size, or thatdecrease in size in the distal-to-proximal direction. In addition, insome embodiments, the first (i.e., distal) loop in a subsequent portionof the elongated member 102 may have a width that is smaller than awidth of the last (i.e., proximal) loop in a previous portion of theelongated member 102. Alternatively, in other embodiments, the first(i.e., distal) loop in a subsequent portion of the elongated member 102may have a width that is larger than a width of the last (i.e.,proximal) loop in a previous portion of the elongated member 102.

In one or more embodiments described herein, the embolic device 100 mayoptionally further include a distal loop at the distal end of theembolic device 100, wherein the distal loop has a diameter that is 75%of less of the diameter of the loop proximal to the distal loop. As usedin this specification, a “diameter” of a loop does not necessarily implythat the loop has a circular shape, and the term “diameter” may refer toa width of a loop, which may or may not be circular in shape. Forexample, a diameter of a loop may refer to a largest width of the loopin some cases.

Also, in one or more embodiments described herein, the embolic device100 may optionally further include a distal coil at the distal end ofthe embolic device 100. In one implementation, if the elongated member102 of the embolic device 100 is formed from a braid, the distal coilmay be formed from one or more strands of the braid. In anotherimplementation, a separate coil may be provided as the distal coil, andis then attached to the distal end of the elongated member 102.

In addition, in one or more embodiments described herein, the embolicdevice 100 may optionally further include a proximal coil at theproximal end of the embolic device 100. In one implementation, if theelongated member 102 of the embolic device 100 is formed from a braid,the proximal coil may be formed from one or more strands of the braid.In another implementation, a separate coil may be provided as theproximal coil, and is then attached to the proximal end of the elongatedmember 102. The proximal coil is advantageous because it may providestiffness transition from the embolic device 100 to the shaft 30.

Also, in one or more embodiments described herein, a proximal portion ofthe embolic device 100 may have a stiffness (e.g., bending stiffnessand/or axial stiffness) that is different from a stiffness (e.g.,bending stiffness and/or axial stiffness) of a distal portion of theembolic device 100. In some embodiments, the proximal portion of theembolic device 100 may have a column strength that is different from acolumn strength of the distal portion. For example, the column strengthof the proximal portion of the embolic device 100 may be higher than acolumn strength of the proximal portion of the embolic device 100. Thisis advantageous because it allows the embolic device 100 to be pusheddistally inside the catheter 20 without buckling. The relativedifference in column strength and/or stiffness may be achieved usingmetallurgical heat treat condition, by variation in the cross-sectionaldimension, and/or by varying number of strands in a braided structure,along the length of the elongated member 102.

Also, in one or more embodiments described herein, if the elongatedmember 102 is a braided structure, the braid angle of the strands alongthe length of the member 102 may be varied in order to change thestiffness along the length of the elongated member 102. For example, insome embodiments, a proximal portion of the elongated member 102 and adistal portion of the elongated member 102 may have the same number ofstrands, but the braid angle (e.g., angle formed by the strands withrespect to the longitudinal axis of the member 102) of the strands inthe proximal portion may be larger than the braid angle of the strandsin the distal portion, thereby making the proximal portion of theelongated member 102 stiffer than the distal portion of the elongatedmember 102. In other embodiments, the braid angle of the strands in thedistal portion of the elongated member 102 may be larger than the braidangle of the strands in the proximal portion of the elongated member102, thereby making the second portion of the elongated member 102softer than the first portion of the elongated member 102. Also, in someembodiments, the braid angle of the strands along the length of themember 102 may vary gradually.

In addition, in some embodiments, the three-dimensional structurecomprises a first plurality of loops 400, and wherein loop widths, loopcurvatures, braid widths, braid angles, or any combination of theforegoing, of the respective ones of the first plurality of loops 400increase or decrease along a length of the elongated member 102 formingthe three-dimensional structure 112.

In addition, in some embodiments, the three-dimensional structure 112comprises a plurality of loops 400, and wherein angles between adjacentones of the plurality of loops 400 increase or decrease along a lengthof the elongated member 102 forming the three-dimensional structure 112.

Furthermore, it should be noted that the embolic device 100 is notlimited to the examples described herein, and that the embolic device100 may have other configurations in other embodiments. For example, inother embodiments, the embolic device 100 may be configured to formother three-dimensional structures that are different from the onesdescribed herein.

In further embodiments, the embolic device 100 is not configured to filla body cavity from the periphery of the body cavity towards the center,nor is it configured to fill the body cavity from the center towards theperiphery of the body cavity. Instead, the embolic device may beconfigured to fill the body cavity from one side of the body cavitytowards an opposite side. Alternatively, the embolic device may beconfigured to fill the body cavity in a random manner.

Various techniques may be used to form the embolic device 100. In someembodiments, the elongated member 102 may be wrapped around one or moremandrels to form a desired shape. The mandrel(s) may include multipleposts configured to allow the elongated member 102 to wrap there-around.The sizes of the posts will dictate the loop sizes of the loops to beformed. Also, the relative orientation of the posts will dictate therelative angles among the loops to be formed. After the elongated member102 has been wrapped around the mandrel(s), the elongated member 102 maybe chemically treated and/or heat treated to achieve the deployed shapeof the elongated member 102, and/or to provide different mechanicalproperties for different portions of the elongated member 102.

In some embodiments, controlled heating and/or local heating may beperformed so that the different segments along the length of theelongated member 102 will have different phase transition temperatures.This can be done for example by laser heating. In particular, a firstheat treatment condition may be applied to a first set of segments(e.g., segment 302, 412, etc.) along the length of the elongated member102, so that their transformation temperature is higher than bodytemperature (37C). Accordingly, these segments will retain theirMartensite phase when the device is deployed into a treatment site. Theyare therefore considered to be irreversible Martensite segments sincethere is no phase transformation of Martensite into Austenite. Incontrast, a second heat treatment condition may be applied to a secondset of segments (e.g., segments 300, 304, 410, 414, etc.), so that theirtransformation temperature is lower than body temperature (37C). Thesesegments will have a phase transformation from Martensite to Austenitewhen the embolic device 100 is deployed into the treatment site. Theyare considered to be reversible Martensite segments. In general, thermalinduced Martensite occurs as twinned Martensite, and the twinnedMartensite structures can turn into detwinned structures by deformingthe material in the martensitic condition in response to the materialreaching a transition temperature.

In other embodiments, deformation strain control may be applied to thedifferent segments along the length of the elongated member 102. Inparticular, a first strain condition may be applied to a first set ofsegments (e.g., segments 302, 412, etc.) in such a way that the strainexceeds its recoverable limit of the Martensite phase, and therefore theMartensite phase cannot transfer to Austenite phase when the embolicdevice is deployed into the treatment site. These segments retainMartensite phase all the time, and therefore are considered to beirreversible Martensite segments. On the other hands, a second straincondition may be applied to a second set of segments (e.g., segments300, 304, 410, 414, etc.) in such a way that the strain level is withintheir recoverable limit, and therefore the Martensite phase willtransfer to Austenite phase when the embolic device 100 is deployed intothe treatment site. These segments are therefore considered to bereversible Martensite segments.

In other embodiments, parts of the elongated member 102 may be coveredby a shielding material while other parts of the elongated member 102are chemically and/or heat treated. This allows different parts of theelongated member 102 to be formed having different mechanicalproperties. For example, this technique may be used to make irreversibleMartensite segments and reversible Martensite segments along the lengthof the elongated member 102.

In further embodiments, a combination of the above techniques may beemployed to create the irreversible Martensite segments and thereversible Martensite segments along the length of the elongated member102.

Other techniques for shaping an elongated member may be used in otherembodiments to form the embolic device 100.

After the elongated member 102 has been formed to have the deployedshape (e.g., like the examples shown in FIG. 4 and FIG. 6 ), and to haveboth irreversible Martensite segments (e.g., segments 302, 412, etc.)and reversible Martensite segments (e.g., segments 300, 304, 410, 414,etc.) along the length of the elongated member 102, the elongated member102 may be further treated to form a delivery shape (e.g., like theexamples shown in FIG. 3 and FIG. 5 ). In some embodiments, such may beaccomplished using thermal cycling. For example, the elongated member102 (already formed to have the deployed shape) may be subject torepeated heating and cooling while the elongated member 102 is placed ina desired delivery shape to be formed. In one technique, the elongatedmember 102 may be tensioned into a straight profile while subjecting itto repeated heating and cooling. In some embodiments, the heating may beperformed heat the elongated member 102 to a temperature that is higherthan 80° C., or more preferably higher than 90° C. (e.g., 100° C.), ormore preferably higher than 100° C. Also, in some embodiments, thecooling may be performed to cool the elongated member 102 to atemperature that is below 10° C., or more preferably below 0° C., ormore preferably below −10° C. This technique can be employed to createthe embolic device 100 so that it has a first shape (delivery shape)when it is in room temperature, and a second shape (deployed shape) whenit is in body temperature, such as when the embolic device 100 isdeployed inside the patient. FIG. 7 is a stress-strain graph,particularly showing an effect of thermal cycling. As can be seen fromthe graph, when the elongated member 102 is subjected to heating andcooling, thermal stress is applied to the elongated member 102, therebyshifting the stress-strain curve of the elongated member 102. If theheating and cooling is repeated for additional cycle(s), additionalthermal stress is applied to the elongated member 102, thereby shiftingthe stress-strain curve further.

It should be noted that the transition temperature at which the embolicdevice 100 will change from the delivery shape to the deployed shape canbe selectively configured using material composition and/ormanufacturing process. For example, the Austenite finishing temperaturemay be selected for the manufacturing process for a certain givenmaterial so that the finished product will have a desired transitiontemperature.

FIGS. 8A-8B illustrate a method of using the medical device 10 of FIG. 1to treat an aneurysm 700. When using the medical device 10, the catheter20 is first inserted into a blood vessel 702 of a patient through anincision. The catheter 20 is then advanced distally until the distal end22 of the catheter 20 is at the aneurysm 700.

In some embodiments, the catheter 20 may be steerable. For example, thecatheter 20 may include one or more steering wires configured to steerthe distal end 22 of the catheter 20 in one or more directions. In otherembodiments, the catheter 20 may not be steerable. Instead, a guidewiremay first be used to access the target site. Then the catheter 20 may bedisposed over the guidewire, and advanced distally using the guidewire.In such cases, the catheter 20 may include a separate channel foraccommodating the guidewire.

After the distal end 22 of the catheter 20 is desirably placed, theshaft 30 (shown in FIG. 1 ) is then advanced to push the embolic device100 distally until a first distal portion of the embolic device 100 isoutside the catheter 20 (FIG. 8A). The embolic device 100 has a straightprofile when in room temperature residing inside the catheter 20. Thestraight profile is due to the embolic device 100 being in roomtemperature, and it is not due to any mechanical straightening imposedby the catheter 20. Accordingly, the embolic device 100 can be easieradvanced distally. This feature also allows a longer embolic device 100to be delivered if needed. As shown in the figure, the first portion ofthe elongated member 102 responds to body temperature by changing fromits relatively straight shape to form a first part of thethree-dimensional structure 112 when the first portion of the elongatedmember 102 is unconfined outside the catheter 20. In particular, thereversible Martensite segments (e.g., segments 300, 304, 410, 414, etc.)along the elongated member 102 change phase to become Austenite segmentsin response to body temperature. These Austenite segments havecurvilinear profiles to provide the delivery shape for the portions ofthe elongated member 102 that has been deployed. The irreversibleMartensite segments (e.g., segments 302, 412, etc.) along the elongatedmember 102 remains in the Martensite phase. These irreversibleMartensite segments are softer compared to the reversible Martensitesegments, and therefore they are easier to be bent in response to force.Accordingly, as the first part of the three-dimensional structure 112 isdelivered into the aneurysm, the loops of the three-dimensionalstructure 112 are pressed towards the wall of the aneurysm, whichimposes a force onto the irreversible Martensite segments. Thesesegments bend in response to the force, thereby allowing the deliveredfirst part of the three-dimensional structure 112 to better conform tothe shape of the aneurysm 700.

In the illustrated example, the first part of the three-dimensionalstructure 112 has a shape that corresponds with an inner wall of theaneurysm. The first part of the three-dimensional structure 112,represented schematically by the dashed line in FIG. 8A, provides aframe defining the cavity 118 for accommodating subsequent portions ofthe embolic device 100 to be delivered. As shown in the figure, thefirst part of the three-dimensional structure 112 also provides ascaffolding across a neck 704 of an aneurysm 700, which assists incontaining subsequent portion(s) of the elongated member 102 of theembolic device 100 to be delivered into the cavity 118.

Next, the shaft 30 may be advanced further to push a subsequent portionof the embolic device 100 out of the catheter 20 (FIG. 8B). As shown inthe figure, the subsequent portion forms a second part of thethree-dimensional structure 112 when the subsequent portion isunconfined outside the catheter 20. The second part of thethree-dimensional structure 112 has a shape that allows it to fill atleast some of the space in the cavity 118 defined by the first part ofthe three-dimensional structure 112. As shown in the figure, thescaffolding across the neck 704 of the aneurysm provided by the firstpart of the three-dimensional structure 112 prevents the second part ofthe three-dimensional structure 112 from escaping or falling out of thecavity 118 of the first part of the three-dimensional structure 112 andout of the aneurysm.

As similarly discussed with reference to the first part of thethree-dimensional structure 112, for the second part of thethree-dimensional structure 112, the reversible Martensite segmentsalong the elongated member 102 change phase to become Austenite segmentsin response to body temperature. These Austenite segments havecurvilinear profiles to provide the delivery shape for the portions ofthe elongated member 102 that has been deployed. On the other hand, theirreversible Martensite segments along the elongated member 102 remainsin the Martensite phase. These irreversible Martensite segments aresofter compared to the reversible Martensite segments, and thereforethey are easier to be bent in response to force. Accordingly, as thesecond part of the three-dimensional structure 112 is delivered into theaneurysm, the loops of the three-dimensional structure 112 are pressedtowards the wall of the aneurysm (or towards the first part of thethree-dimensional structure 112), which imposes a force onto theirreversible Martensite segments. These segments bend in response to theforce, thereby allowing the delivered second part of thethree-dimensional structure 112 to better conform to the shape of thecavity to be filled.

In some embodiments, the distal end of the shaft 30 abuts against theproximal end of the elongated member 102, and is not mechanicallyattached to the proximal end of the elongated member 102. In such cases,the elongated member 102 becomes decoupled from the remaining part ofthe medical device 10 as soon as the proximal end of the elongatedmember 102 is pushed out of the catheter 20. In other embodiments, thedistal end of the shaft 30 may be mechanically connected to the proximalend of the elongated member 102, such as via a mechanical connector thatis operable to disengage the proximal end of the elongated member 102from the shaft 30. In further embodiments, the distal end of the shaft30 may be mechanically connected to the proximal end of the elongatedmember 102 via a disintegratable link, such as a link that can bedisintegrated in response to application of a current. Mechanicalconnectors and disintegratable links are well known in the art, andtherefore will not be described in further detail.

As illustrated in the above embodiments, the embolic device 100 isadvantageous because the softer individual discrete irreversibleMartensite segments provide some flexibility for the embolic device 100,thereby allowing the embolic device 100 to bend easily in response toforce. While certain discrete parts (the irreversible Martensitesegments) of the embolic device 100 can be more easily bent, a majorityof other parts (i.e., the reversible Martensite segments) of the embolicdevice 100 remains relatively stiffer compared to the irreversibleMartensite segments, thereby allowing the shape of most of the parts ofthe embolic device 100 to be maintained within the body cavity. Inaddition, the embolic device 100 is also advantageous because it has adelivery shape within the catheter 20 that is relatively straightcompared to its deployed shape. This allows the embolic device 100 to beadvanced distally relative to the catheter 20 easily without use ofsignificant axial pushing force, and reduces the risk of the embolicdevice 100 buckling within the catheter 20.

In some embodiments, multiple embolic devices 100 may be provided withdifferent respective lengths. In such cases, before one of the embolicdevices 100 is selected for treating an aneurysm, a doctor may measure asize of the aneurysm to be treated. For example, the doctor may performmeasurement using one or more images of the aneurysm to determine thesize of the aneurysm. The size may be a cross-sectional dimension of theaneurysm, a cross-sectional area of the aneurysm, a volume of theaneurysm, etc. After a size of the aneurysm has been determined, one ofthe embolic devices 100 may then be selected based on the size of theaneurysm. For example, a longer embolic device 100 may be selected toocclude a larger aneurysm.

FIG. 9 illustrates a method 800 of occluding a body lumen. The method800 is performed by an embolic device having an elongated member, theelongated member comprising a first segment, a second segment, and athird segment, wherein the second segment is between the first segmentand the third segment. The method 800 includes: undergoing a first shapechange by the first segment of the elongated member in response to bodytemperature (item 802); undergoing a second shape change by the secondsegment of the elongated member in response to force (item 804); andundergoing a third shape change by the third segment of the elongatedmember in response to the body temperature (item 806).

In some embodiments, the embolic device in the method 800 may be theembolic device 100 described herein.

Optionally, in the method, the first segment is martensitic when thefirst segment is in the room temperature, and is austenitic when thefirst segment is in the body temperature; and wherein the second segmentis martensitic when the second segment is in the room temperature, andis also martensitic when the second segment is in the body temperature.

Optionally, in the method, the first segment forms a first part of aloop, and the third segment forms a second part of the loop, in responseto the body temperature.

Optionally, in the method, the first segment forms a first loop, and thethird segment forms a second loop, in response to the body temperature.

Optionally, in the method, the first segment has a first length, thesecond segment has a second length, and the third segment has a thirdlength; and wherein the second length of the second segment is shorterthan the first length of the first segment, and is also shorter than thethird length of the third segment.

Optionally, in the method, the second length of the second segment thatis between the first segment and the third segment is less than 50% ofthe first length of the first segment, and is also less than 50% of thethird length of the third segment.

Optionally, in the method, the elongated member has a distal end and aproximal end opposite from the distal end, and wherein the embolicdevice further comprises a fourth segment that includes the proximalend; and wherein the fourth segment is martensitic when in the roomtemperature, and is also martensitic when the fourth segment is the bodytemperature.

Optionally, in the method, the three-dimensional structure comprises aplurality of loops, and wherein the first segment, the second segment,and the third segment are parts of one of the loops.

Optionally, in the method, the elongated member further comprises afourth segment, a fifth segment, and a sixth segment that are parts ofanother one of the loops; wherein the fifth segment is between thefourth segment and the sixth segment; wherein the fourth segment and thesixth segment are martensitic when the fourth segment and the sixthsegment are in the room temperature, and are austenitic when the fourthsegment and the sixth segment are in the body temperature; and whereinthe fifth segment is martensitic when the fifth segment is in the roomtemperature, and is also martensitic when the fifth segment is in thebody temperature.

The following items are exemplary features of embodiments describedherein. Each item may be an embodiment itself or may be a part of anembodiment. One or more items described below may be combined with otheritem(s) in an embodiment.

Item 1: An embolic device for placement in a body lumen, includes: anelongated member having a linear configuration when in room temperature,the elongated member being configured to form a first three-dimensionalstructure in response to body temperature; wherein the elongated membercomprises a first segment, a second segment, and a third segment, thesecond segment being located between the first segment and the thirdsegment; wherein the first segment and the third segment are configuredto change their respective shapes in response to the body temperature;and wherein the second segment that is located between the first segmentand the third segment has a shape that is independent of the bodytemperature.

Item 2: The first segment is configured to form a first part of a loop,and the third segment is configured to form a second part of the loop inresponse to the body temperature.

Item 3: The first segment is configured to form a first loop, and thethird segment is configured to form a second loop, in response to thebody temperature.

Item 4: The first segment has a first length, the second segment has asecond length, and the third segment has a third length; and wherein thesecond length of the second segment is shorter than the first length ofthe first segment, and is also shorter than the third length of thethird segment.

Item 5: The second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Item 6: The elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when the fourth segment is in the roomtemperature, and is also martensitic when the fourth segment is in thebody temperature.

Item 7: The first segment is martensitic when the first segment is inthe room temperature, and is austenitic when the first segment is in thebody temperature.

Item 8: The second segment is martensitic when the second segment is theroom temperature, and is martensitic when the second segment is in thebody temperature.

Item 9: The three-dimensional structure comprises a plurality of loops,and wherein the first segment, the second segment, and the third segmentare parts of one of the loops.

Item 10: The elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment areconfigured to change their respective shapes in response to the bodytemperature; and wherein the fifth segment that is located between thefourth segment and the sixth segment has a shape that is independent ofthe body temperature.

Item 11: An embolic device for placement in a body lumen, includes: anelongated member having a linear configuration when in room temperature,the elongated member being configured to form a first three-dimensionalstructure in response to body temperature; wherein the elongated membercomprises a first segment, a second segment, and a third segment, thesecond segment being located between the first segment and the thirdsegment; wherein the first segment is martensitic when the first segmentis in the room temperature, and is austenitic when the first segment isin the body temperature; and wherein the second segment is martensiticwhen the second segment is in the room temperature, and is alsomartensitic when the second segment is in the body temperature.

Item 12: The first segment is configured to form a first part of a loop,and the third segment is configured to form a second part of the loop,in response to the body temperature.

Item 13: The first segment is configured to form a first loop, and thethird segment is configured to form a second loop, in response to thebody temperature.

Item 14: The first segment has a first length, the second segment has asecond length, and the third segment has a third length; and wherein thesecond length of the second segment is shorter than the first length ofthe first segment, and is also shorter than the third length of thethird segment.

Item 15: The second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Item 16: The elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when in the room temperature, and isalso martensitic when the fourth segment is the body temperature.

Item 17: The three-dimensional structure comprises a plurality of loops,and wherein the first segment, the second segment, and the third segmentare parts of one of the loops.

Item 18: The elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment aremartensitic when the fourth segment and the sixth segment are in theroom temperature, and are austenitic when the fourth segment and thesixth segment are in the body temperature; and wherein the fifth segmentis martensitic when the fifth segment is in the room temperature, and isalso martensitic when the fifth segment is in the body temperature.

Item 19: A method of occluding a body lumen performed by an embolicdevice having an elongated member, the elongated member comprising afirst segment, a second segment, and a third segment, wherein the secondsegment is between the first segment and the third segment, includes:undergoing a first shape change by the first segment of the elongatedmember in response to body temperature; undergoing a second shape changeby the second segment of the elongated member in response to force; andundergoing a third shape change by the third segment of the elongatedmember in response to the body temperature.

Item 20: The first segment is martensitic when the first segment is inthe room temperature, and is austenitic when the first segment is in thebody temperature; and wherein the second segment is martensitic when thesecond segment is in the room temperature, and is also martensitic whenthe second segment is in the body temperature.

Item 21: The first segment forms a first part of a loop, and the thirdsegment forms a second part of the loop, in response to the bodytemperature.

Item 22: The first segment forms a first loop, and the third segmentforms a second loop, in response to the body temperature.

Item 23: The first segment has a first length, the second segment has asecond length, and the third segment has a third length; and wherein thesecond length of the second segment is shorter than the first length ofthe first segment, and is also shorter than the third length of thethird segment.

Item 24: The second length of the second segment that is between thefirst segment and the third segment is less than 50% of the first lengthof the first segment, and is also less than 50% of the third length ofthe third segment.

Item 25: The elongated member has a distal end and a proximal endopposite from the distal end, and wherein the embolic device furthercomprises a fourth segment that includes the proximal end; and whereinthe fourth segment is martensitic when in the room temperature, and isalso martensitic when the fourth segment is the body temperature.

Item 26: The three-dimensional structure comprises a plurality of loops,and wherein the first segment, the second segment, and the third segmentare parts of one of the loops.

Item 27: The elongated member further comprises a fourth segment, afifth segment, and a sixth segment that are parts of another one of theloops; wherein the fifth segment is between the fourth segment and thesixth segment; wherein the fourth segment and the sixth segment aremartensitic when the fourth segment and the sixth segment are in theroom temperature, and are austenitic when the fourth segment and thesixth segment are in the body temperature; and wherein the fifth segmentis martensitic when the fifth segment is in the room temperature, and isalso martensitic when the fifth segment is in the body temperature.

Although particular embodiments have been shown and described, it willbe understood that it is not intended to limit the claimed inventions tothe preferred embodiments, and it will be obvious to those skilled inthe art that various changes and modifications may be made withoutdepartment from the spirit and scope of the claimed inventions. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than restrictive sense. The claimed inventions areintended to cover alternatives, modifications, and equivalents.

1. An embolic device for placement in a body lumen, the embolic device comprising: an elongated member having a first configuration when at room temperature, the elongated member being configured to form a three-dimensional structure in response to body temperature, the three-dimensional structure having a second configuration that is different from the first configuration; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment being between the first segment and the third segment; wherein the first segment and the third segment are configured to change their respective shapes in response to the body temperature; and wherein the first segment is martensitic when the first segment is at the room temperature, and is austenitic when the first segment is at the body temperature; and wherein the second segment that is between the first and third segments is softer than the first and third segments.
 2. The embolic device of claim 1, wherein the first segment is configured to form a first part of a loop, and the third segment is configured to form a second part of the loop.
 3. The embolic device of claim 1, wherein the first segment is configured to form a first loop, and the third segment is configured to form a second loop.
 4. The embolic device of claim 1, wherein the first segment has a first length, the second segment has a second length, and the third segment has a third length; and wherein the second length of the second segment is shorter than the first length of the first segment, and is also shorter than the third length of the third segment.
 5. The embolic device of claim 1, wherein the second segment comprises a martensitic segment.
 6. The embolic device of claim 1, wherein the second segment is martensitic when the second segment at the room temperature, and is martensitic when the second segment is at the body temperature.
 7. The embolic device of claim 1, wherein the three-dimensional structure comprises a plurality of loops, and wherein the first segment, the second segment, and the third segment are parts of one of the loops.
 8. An embolic device for placement in a body lumen, the embolic device comprising: an elongated member having a first configuration when at room temperature, the elongated member being configured to form a three-dimensional structure in response to body temperature, the three-dimensional structure having a second configuration that is different from the first configuration; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment being between the first segment and the third segment; wherein the first segment is martensitic when the first segment is at the room temperature, and is austenitic when the first segment is at the body temperature; and wherein the second segment is martensitic when the second segment is at the room temperature, and is also martensitic when the second segment is at the body temperature.
 9. The embolic device of claim 8, wherein the first segment is configured to form a first part of a loop, and the third segment is configured to form a second part of the loop.
 10. The embolic device of claim 8, wherein the first segment is configured to form a first loop, and the third segment is configured to form a second loop.
 11. The embolic device of claim 8, wherein the first segment has a first length, the second segment has a second length, and the third segment has a third length; and wherein the second length of the second segment is shorter than the first length of the first segment, and is also shorter than the third length of the third segment.
 12. The embolic device of claim 8, wherein the three-dimensional structure comprises a plurality of loops, and wherein the first segment, the second segment, and the third segment are parts of one of the loops.
 13. The embolic device of claim 8, wherein the second segment comprises a martensitic segment.
 14. An embolic device for placement in a body lumen, the embolic device comprising: an elongated member having a first configuration when at room temperature, the elongated member being configured to form a three-dimensional structure in response to body temperature, the three-dimensional structure having a second configuration that is different from the first configuration; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment extending from an end of the first segment to an end of the third segment; wherein the first segment and the third segment are configured to change their respective shapes in response to the body temperature; wherein the first segment has a first length, the second segment has a second length that is an entire length of the second segment, and the third segment has a third length; wherein an entirety of the first segment has a first material property, an entirety of the second segment has a second material property that is different from the first material property, and an entirety of the third segment has a third material property that is different from the second material property; and wherein the second length of the second segment is shorter than the first length of the first segment, and is also shorter than the third length of the third segment.
 15. The embolic device of claim 14, wherein the second length of the second segment is less than 50% of the first length of the first segment, and is also less than 50% of the third length of the third segment.
 16. The embolic device of claim 14, wherein the first material property is the same as the third material property.
 17. The embolic device of claim 14, wherein the first segment is martensitic when the first segment is at the room temperature, and is austenitic when the first segment is at the body temperature.
 18. The embolic device of claim 14, wherein the second segment is martensitic when the second segment is at the room temperature, and is also martensitic when the second segment is at the body temperature.
 19. The embolic device of claim 14, wherein the first segment is configured to form a first part of a loop, and the third segment is configured to form a second part of the loop.
 20. The embolic device of claim 14, wherein the first segment is configured to form a first loop, and the third segment is configured to form a second loop. 